JENNINGS VACUUM CAPACITOR
These might be very useful in TESLA COILS!
Jennings vacuum capacitors are small, vacuum-dielectric
units intended principally for use as all or part of the
plate tank capacitance in radio-frequency amplifiers or
oscillators. They are also frequently used as
high-voltage coupling and by-pass capacitors at high
frequencies and as high-voltage neutralizing capacitors,
when used in conjunction with small high-voltage variable
capacitors having a small capacitance range. The use of
a vacuum as a dielectric permits the construction of a
comparatively small lightweight capacitor for a given
voltage rating and capacitance. In addition, the effects
of dust and atmospheric conditions on the capacitor
are eliminated by sealing the plates within a glass
The sum of the peak R-F and D-C voltages must not exceed
the peak voltage rating of the capacitor!
Jennings vacuum capacitors are provided with terminals
which allow the use of standard 60-ampere fuse clips for
mounting. These clips must be kept clean and must at all
times make firm and positive contact with the capacitor
terminals. Failure to maintain a low-resistance contact
to the capacitor terminals may result in excessive
heating and permanent damage to the capacitor seals.
Taken From: Tesla List
( mod1-at-pupman-dot-com )
I would describe it as a diode as it has only two pins,
that is cylindrical with a diameter of approximately 2"
and length of 6". One pin on each end. It is a vacuum
Typical values are in the 10-100 pF range with voltage
ratings in the kilovolt range. The Jennings ones are
usually made of copper, Eimac used other materials in
the ones I have seen. They can be used in tube coils
as they are low loss (vacuum). I have also heard of a
few people who used them as experimental spark gaps,
although they foul after a while (quiet though)
Mark S. Rzeszotarski, Ph.D., Senior Physicist, Radiology Dept.
The Mt. Sinai Medical Center, Cleveland, Ohio 44106
Assistant Professor, Case Western Reserve University
Departments of Radiology and Biomedical Engineering
Voice:216-421-4689 FAX:216-421-5343 E-mail:msr7-at-po.cwru.edu